This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 11-372193, filed Dec. 28, 1999; and No. 2000-004343, filed Jan. 13, 2000, the entire contents of which are incorporated herein by reference.
The present invention relates to a resin film forming method and a resin film forming apparatus employing said method, particularly, to a method and apparatus for simultaneously forming resin films in a plurality of resin film forming regions arranged on one surface of a film.
In, for example, a TAB (Tape Automated Bonding) system, which is one of mounting technologies of a semiconductor chip such as an IC or an LSI, a long base film is transferred by the so-called roll-to-roll method so as to coat semiconductor chips arranged at a predetermined interval in the longitudinal direction of the base film with resin, thereby forming a sealing resin film.
FIG. 6 schematically shows, as an example, the construction of a conventional resin film forming apparatus used in the TAB system. As shown in the drawing, the conventional resin film forming apparatus comprises a base film supply section 1, a resin coating section 2, a drying section 3, a tension imparting section 4 and a base film take-up section 5 as viewed from the left side toward the right side. In this case, a laminate structure consisting of a long base film 11 and a protective spacer 12 is rolled about a reel 13 as shown in FIG. 7, and the resultant roll is arranged in the base film supply section 1.
The base film 11 is constructed as shown in, for example, FIG. 8. To be more specific, sprocket holes 21 are arranged at a pitch P on both sides in the width direction of the base film 11. A device hole 23 and an outer lead hole 24 are formed in each device region 22 of the base film 11. Also, a large number of input wirings 25 and a large number of output wirings 26 are formed in each device region 22 on the lower surface of the base film 11. Further, a semiconductor chip 27 is mounted on the base film 11 by coupling wirings 25 and 26 within each device hole 23.
If the base film 11 and the spacer 12 are released from the reel 13 in the base film supply section 1, the spacer 12, which is obstructive to the resin coating, is wound about a spacer reel 31 so as to be recovered. On the other hand, the base film 11 released from the reel 13 is supplied into the resin coating section 2 through a guide roller 32.
Two nozzles 33 and 34 are arranged within the resin coating section 2. These two nozzles 33, 34 are moved in X, Y and Z directions by an XYZ robot (not shown), and that portion of the base film 11 in which two adjacent semiconductor chips 27 are mounted is coated with resin so as to form a resin film (not shown). The two nozzles 33 and 34 are used for improving the efficiency of the resin coating operation.
Then, the base film 11 is transferred into the drying section 3. In the drying section 3, the base film 11 passes through first and second guide rollers 35 and 36, and the resin film coated in the resin coating section 2 is dried by a heater (not shown). The base film 11 further passes through two tension imparting rollers 37 and 38 arranged within the tension imparting section 4 so as to be transferred into the base film take-up section 5. In the base film take-up section 5, the base film 11 is superposed with another spacer 40 released from another spacer reel 39 and the resultant superposed structure is wound up about another reel 41.
It should be noted that the pitch P of the sprocket holes 21 of the base film 11 is defined to be, for example, 4.75 mm in JIS (Japanese Industrial Standards), and the design and manufacture are performed on the basis of the sprocket holes 21 thus defined. In the case of FIG. 8, a single device region 22 corresponds to 6 sprocket holes 21. The length of the base film 11 corresponding to the device region 22, hereinafter referred to as a length LD of the device region 22, is called a 6-pitch length. Also, where the base film 11 is transferred over a distance corresponding to the 6 sprocket holes 21, it is stated that the base film 11 is transferred by 6 pitches.
In the resin coating section 2, the base film 11 is intermittently transferred, and the base film 11 is coated with resin by using the nozzles 33 and 34 while the transfer of the base film 11 is stopped. In this case, the time required for a single resin coating step is equal to the sum of the resin coating time and the base film transfer time. However, the base film transfer time is very short, compared with the resin coating time. If the base film transfer time is neglected, the time required for a single resin coating step is determined by the resin coating time. Suppose the resin coating time is m seconds. It should be noted in this connection that, in the resin coating section 2, the mounting portions of two semiconductor chips 27 are simultaneously coated with the resin in a single resin coating step. It follows that the base film 11 is transferred by 12 pitches in m seconds.
On the other hand, it is necessary for the base film 11 to be transferred through the drying section 3 over a time required for drying sufficiently the coated resin film. Suppose M minutes are required for sufficiently drying the coated resin film. In this case, the base film 11 transferred by 12 pitches in m seconds within the resin coating section 2 passes through the drying section 3 over M minutes. If the base film 11 is transferred by 6 pitches in m seconds, the time required for the base film 11 to pass through the drying section 3 is 2M minutes, i.e., twice M minutes noted above.
The length LD of the device region 22 is not limited to 6 pitch length. For example, it is possible for the length LD to be 3 pitch length. Even in the case of the 3 pitch length, the resin coating time of m seconds is required for stopping the transfer of the base film 11 and coating the base film 11 with resin by using the nozzles 33 and 34. Therefore, where the length LD of the device region 22 is equal to the 3 pitch length, the transfer speed of the base film 11 within the resin coating section 2 is set such that the base film 11 is transferred by 6 pitches in m seconds in a single resin coating step. In other words, the transfer distance of the base film 11 transferred in a single resin coating step is half the transfer distance in the case where the length LD of the device region 22 is equal to the 6 pitch length. As a result, the base film 11 passes through the drying section 3 over 2M minutes.
As described above, in the conventional resin film forming apparatus, the time for the base film 11 to pass through the drying section 3 widely differs, if the length LD of the device region 22 differs. In the example described above, the time for the base film 11 to pass through the drying section is M minutes in the case where the length LD of the device region 22 is equal to the 6 pitch length. However, where the length LD of the device 22 is equal to the 3 pitch length, i.e., half the value noted above, the time for the base film 11 to pass through the drying section is 2M minutes. It should be noted that the coated resin film can be dried sufficiently in M minutes. It follows that, where the length LD of the device region 22 is equal to the 3 pitch length, the base film 11 is caused to take a considerably long time for passing through the drying section, leading to a low productivity. Also, it is conceivable in this case to increase the number of XYZ robots used as the resin coating devices. However, the XYZ robot is costly. In addition, it is necessary to set with a high accuracy the positions of the nozzles mounted to each XYZ robot. Such being the situation, it is substantially impossible to increase the number of XYZ robots in the system in which nozzles are mounted to each of the XYZ robots set at different positions under different conditions. Alternatively, it takes a very long time and, thus, is highly inefficient to increase the number of XYZ robots mounted to the resin film forming apparatus.
An object of the present invention is to provide a resin film forming method, which permits maintaining an optimum productivity in conformity with the length of the device region, with the time for a base film to pass though a drying section being set substantially constant even if the length of the device region differs, and a resin film forming apparatus to which the particular method of the present invention can be applied.
According to a first aspect of the present invention, there is provided a resin film forming method, comprising the steps of transferring a long film having resin film forming regions arranged at a pitch LD; simultaneously forming resin films in the k-number of resin film forming regions arranged on one surface of the film by using the k-number of nozzles arranged at a predetermined interval on a path through which the film is transferred; and transferring the film by a predetermined distance for the drying treatment; wherein the number k of nozzles is changed to permit the drying time to fall within a predetermined period in accordance with the length LD of the each of the resin film forming regions arranged on the one surface of the film.
According to a second aspect of the present invention, there is provided a resin film forming apparatus, comprising transfer means for transferring a long film having resin film forming regions arranged on one surface thereof at a pitch LD; a resin film forming mechanism including a plurality of nozzles arranged apart from each other on the path through which the film is transferred, and a nozzle holder to which q-number of the nozzles can be mounted and k-number of nozzles are selectively mounted in accordance with the length LD of the resin film forming region, resin films being formed simultaneously in k-number of resin film forming regions among the resin film forming regions arranged on the one surface of the film; and drying means for drying the film having the resin films formed thereon; wherein the transfer distance of the film transferred after formation of the resin films can be set substantially constant by increasing or decreasing the number k of nozzles mounted to the nozzle holder in inverse proportion to the length LD of the resin film forming region.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.